Shearing device and method for use in well drilling



Dec. 29,1959 K. M. NICOLSON 2,919,111

SHEARING DEVICE AND METHOD FOR USE IN WELL DRILLING Filed Dec. 30, 1955 4 Sheets-Sheet 1 FIG. 1

INVENTOR KINGSLEV M. NICOLSON f ATZORNEYS Dec. 29, 1959 K. M. NICOLSON 2,919,111

SHEARING DEVICE AND METHOD FOR USE IN WELL DRILLING Filed Dec. 30, 1955 4 Sheets-Sheet 2 INVENTOR K/NGSLE) M N/COLSON Dec. 29, 1959 K. M. NICOLSON SHEARING DEVICE AND METHOD FOR USE IN WELL DRILLING Filed Dec. 50, 1955,

' 4 Sheets-Sheet 3 INVENTOR KINGSLEV M. IV/COLSON Dec. 29, 1959 K. M. NICOLSON 2,919,111

SHEARING DEVICE AND METHOD FOR USE IN WELL DRILLING Filed Dec. 30, 1955 4 Sheets-Sheet 4 United States Patent SHEARING DEVICE AND METHOD FOR USE IN WELL DRILLING Kingsley M. Nicolson, Fullerton, Califi, assignor to California Research Corporation, San Francisco, Calif., a corporation of Delaware Application December 30, 1955, Serial No. 556,685

2 Claims. (Cl. 25'51.8)

This invention relates to a device for closing off the hole of an oil well and more particularly to a device for simultaneously shearing a drilling string and sealing the opening at the top of the hole within which a drilling operation has been taking place.

It is common practice in drilling oil wells to employ a blowout preventer which is mounted on the top of the casing cemented in the hole to eliect some control over the surface openings of the well. This device usually takes one of two forms. One form employs a packing means for selectively sealing or opening the annulus between the well casing and the tubular drill string inserted through it into the hole which is being drilled. The other form employs a packing means for completely sealing or opening the top of the casing when no drill string is present in it. In the latter type the presence of a drill string in the casing will prevent the packing means from closing and thus prevent it from completely closing the opening at the top of the casing. In the former type the packing means is made with a central opening of circular cross-section to accommodate the circumference of the drill string but does not shut off the hole inside the drill string; hence, neither of these types will completely seal oif all openings into the well when a drill string is present in the hole.

In some emergency conditions which can occur during the drilling of an oil well it is most desirable immediately to achieve a complete shut-off of the hole and of the drill string within the hole so that all openings from the well to the surface are completely closed in a manner to prevent leakage or blowout of high-pressure well fluids. Such conditions might arise, for example, if during a drilling operation the well should start to blow out through the drill string. In this circumstance it is most desirable that some means be available to entirely close the hole immediately. It will be appreciated that unless the well is brought under control very quickly, the initial blowout will build up in force and volume within a short period of time and become very hazardous to personnel and destructive to equipment.

A situation of primary interest for the application of the present invention occurs during offshore drilling. When a drilling operation of this type is being done from a boat or a platform which is anchored in a relatively fixed position over the hole, situations can arise where strong currents, winds, rough water, or combinations of these factors can cause the anchors to drag or the anchoring means to fail. Thus the boat or platform will be displaced from its position over the hole to which it remains attached by the drill string. Sufficient force can, through this inadvertence, be placed on the drill string to cause it to part, leaving the wall open to discharge well fluids into the water. It will be appreciated that it is undesirable to contaminate water adjacent inhabitcd beaches with well fluids.

The adverse conditions of wind and water may arise so suddenly that there is not sufficient time to withdraw the drill string from the hole and take the precautions which may ordinarily be available in land operations for closing the hole off. Since the boat or platform is attached to the bottom of the water by the drill string, and hence is not free to move with the displacement of the water, there is presented the possibility that a floating member will be swamped or capsized, with loss of lives and property. Therefore, it is most desirable that some means he provided for detaching the floating member to prevent the hazardous situation from becoming disastrous. Also, for the reasons mentioned heretofore, it is desirable that at the same time the well be closed off in a manner to prevent leakage of well fluids therefrom.

The present invention discloses a device for accomplishing the above-stated purposes. This device comprises a housing which has incorporated in it means to shear a drill string, and to seal ofi in a fluid-tight manner the opening from the well bore. The device is designed to be operable both on the surface of the land and when submerged under water.

It is an object of this invention, therefore, to provide a novel device which will instantly and completely close off a hole during a drilling operation.

A further object of this invention is to provide a device adapted to be afiixed to the top of a casing in an oil Well, in which the device contains a controlled means for shearing a drill string passing through the casing so that a complete shutoff of the oil well may be obtained.

A still further object of this invention is to provide a means for immediately detaching a floating member from a hole which is being drilled during an offshore operation and to close oh the opening of the hole.

Other objects will become apparent as the description of this invention proceeds hereinafter.

This invention will be described in conjunction with the accompanying drawings, in which:

Fig. 1 illustrates in sectional elevation a device incorporating this invention and shows a drill string in place with the parts located as they would be during a drilling operation.

Fig. 2 illustrates in sectional elevation a device incorporating this invention where the drill string has been severed and the opening of the well closed off.

Fig. 3 illustrates in perspective a detail of the device illustrated in Fig. 1.

Fig. 4 illustrates a section taken along the line 4-4 of Fig. 3.

Fig. 5 illustrates in sectional perspective a modified form of a detail of the invention.

Fig. 6 illustrates the invention employed in an offshore drilling operation.

Referring to the embodiment of the invention illustrated in Figs. 1 and 2, the device comprises a housing 10 which is attached to the top portion of the casing 12 which in normal practice is cemented in a well. The housing has an opening 1-4 extending through it in axial alignment with the opening through the casing 12 to permit access to the well. Two power cylinders 16 and 18 are aflixed to the housing in diametrically opposed relationship and are connected to a source of pressurized fluid, notshown, by conduits 20 and 22 respectively. The cylinders are actuated simultaneously to move toward each other or alternatively away from each other by a valving arrangement, not shown but well known to the art. A set of members 24 and 26 are slidably mounted in casing 10 to move transversely across the opening thereof and are connected to the pistons of the power cylinders by piston rods 28 and 30 respectively, as shown in Fig. 2, so that when the power cylinders are actuated the members will come together or alternatively move apart across the opening 14.

In accordance with the present invention the members 24.and 26 are constructed so that when they are forced together they will cause an object placed between them, such as a drill string 32, which in normal drilling operations passes axially through the opening 14, to be sheared transversely of its axis. This is accomplished by providing complementary shearing means on the members 24 and 26 which will cooperate to shear an element extending axially through the housing in a manner to be explained in more detail hereinafter.

In the modification of the present invention illustrated in Figs. 1 and 2, the members 24 and 26 are each made with a semicircular central portion 34 and 36 respectively which have complementary diametrically disposed surfaces adapted to be moved into abutting relationship. A packing material 38 is placed between the body of the member and its central portion and extends laterally across the diametrically disposed face thereof, as indicated by the numeral 40. The packing material is a resilient substance, such as rubber, which will deform under pressure; hence, when the members 24 and 26 are forced into abutment the packing material between the body of the member and its central portion will tend to bulge outwardly to form a fluid-tight seal with the 'surface 42 of the housing as illustrated in Fig. 2, while the packing material extending across the corresponding diametrically disposed faces of the members will abut to form a fluid-tight seal between them. Thus, the opening of the casing will be completely closed in a manner to prevent well fluids from escaping. p

Referring now to Figs. 3 and 4, which illustrate details of the device shown in Figs. 1 and 2, the complementary central portions 34 and 36 are each made of two separable elements 44 and 46. A peripheral groove 48 is placed around each member between the elements to receive an appropriately shaped portion of the packing material to hold it in place and afiix it to the central portion. The element 44 has a semi-circular channel 50 formed in it to receive in close relationship a semicircular projection 52 extending from the element 46. The elements are fastened together as by bolts 54 to form a unitary structure of suiiicient strength to take the loads incurred by shearing the drill string, and are held in place on members 24 and 26 respectively by bolts 55 in a manner to permit restricted relative movement between the central portion and its supporting member.

The elements 46 of the respective central portions have cooperating shearing means'incorporated in them. Central portion 34 has a projection 56 extending from the element 46 radially inwardly beyond the packing material 38. The projection terminates in a shearing edge 58. Central portion 36 has a complementary projection 60 extending radially inwardly and terminating in shearing edge 62. The projections are positioned to overlap in close relationship prior to the time the packing material 40 contacts when the members 24 and 26 approach each other. A recess 64 is provided in central portion 34 to receive the projection 60 of central portion 36, and a recess 66 is provided in central portion 36 to receive projection56. By this means clearance is provided for the projections to permit the members 24 and 26 to come into abutment with each other. Preferably the radially inwardly edges of the projections 56 and 60- are beveled as at 63 to provide sharper shearing edges. The shearing edges are positioned at an angle to their respective diametrically disposed surfaces of the members 24 and 26 to cause them to first overlap at one end of their diametrical extent as the members approach each other. As the approach continues the overlapping of the shearing edges will continuously progress across the opening 14 to provide a more effective shearing action on an object entrapped between them.

It will be appreciated that when a drill string is sheared, the bottom portion of it will drop away from. the members down'into the well and the top portion will spring upwardly out of the way to give clearance for the members 24 and 26 to come together as illustrated in Fig. 2. Thus, when the members are brought together in abutting relationship, any object which has been extending axially through the opening 14 of the housing 10 will be sheared and cleared from the device, permitting the packing means 40 of the'central portions to contact and form a fluid-tight seal.

Fig. 5 illustrates an alternative exemplary embodiment of the invention. In this modification, the central portions 70 and 72 are formed in one piece and the material has an appropriate peripheral groove 73 cut in it to receive the packing means 38. The packing means functions in the same manner as explained heretofore. Central portion 7% has a recess 74 formed in it to receive a blade 76 which is seated snugly in the recess and held in place there by bolts 78. Central portion 72 has a recess 80 to receive a blade 82 which is held in place by bolts 84. The recesses 74 and 80 are positioned and proportioned so that the blades will overlap each other when-the members 24 and 26 come together in the same manner. as described heretofore with reference to-the modification illustrated in Figs. 3 and 4. The recess 74 has a portion 86 underlying blade 76 to receive the blade 82 and the recess 80 is sufficiently deep'to receive the blade 76 when the members are brought into abutment. The radially inwardly extending edges of the complementary. blades are beveled and angularly positioned, as explained heretofore, to provide effective shearing means. In this modification of the invention the blades are easily detachable so that they may be replaced with new blades when necessary.

An exemplary method for employing the present. invention in an offshore drilling operation is shown in Fig. 6. In such an operation a floating member such as a boat 88 is employed to support a derrick 90 and a rotary table 92, together with the other necessary components required for a rotary drilling operation. Before the drilling operation is begun a casing 12 is hung in the water from the ,boat by means of cables 94. Prior to lowering the'casing into the water, the device 10 of the present invention is secured to the top of it in a fluid-tight manner together with a connection for a mud hose 96 and the other apparatus as may be desired. A hanger 98 is affixed to the assemblage to provide a means for attaching the cables 94 to it. While the casing and its appurtenances are suspended from the boat by the cables, a drill string 32 is inserted through it and a hole is made at the bottom of the ocean. The hole is drilled to the depth it is desired to insert the casing and is reamed to a diameter large enough to accept it. With the drill string remaining in the hole, the cables 94 are slacked off so that the casing will follow the drill string into thehole to a position where the device '10 is proximate the bottom of the ocean. The casing is then cemented in the hole in accordance with the practice followed in land operations as disclosed for example in Oil Production Methods by Paine and Stroud, published in 1913 by Western Engineering Publishing Company, San Francisco, California, particularly page 138; Petroleum Production Methods by Suman, First Edition, published in 1921 by Gulf Publishing Company, Houston, Texas, particularly pages 174-177; and Oil-Field Exploration and Development by Beeby- Thompson, published in 1950 by The Technical Press Ltd., Gloucester Road, Kingston Hill, Surrey,'England, particularly page 843. The hydraulic lines 20 and 22 will have been connected to the device 10 prior to the time the casing is lowered into the hole, as will have been the mud line and other hydraulic lines to other parts of the equipment. The hydraulic lines and mud line are wound on a reel 102 which is mounted on board the floating member and the various lines are connected. to appropriate rotary couplings which permits a continuous connection between the hydraulic lines and a source of pressurized hydraulic fluid, and the mud line with the mud tank while the lines are being reeled or unreeled. By this method of operation the device is placed in a position where it can by a suitable valving arrangement be operated from aboard the floating member to sever the drill string and close off the hole, should emergency conditions arise which require these measures.

When the drill string is cut it is relatively a simple matter to free the cables 94 and the mud line and hydraulic lines from the floating member so that it is entirely free. Thus freed, the floating member is better able to move with the displacement of the water or to be maneuvered in a manner to prevent sudden storms from endangering the personnel and equipment aboard. When the hydraulic lines 20 and 22 are detached from the device 10, the force of the well fluids under pressure, acting on the members 24 and 26, will hold them closed and preserve the seal at the top of the casing to prevent any leakage therefrom.

It is obvious that other modifications than those illustrated may be made, employing the inventive concept without departing from it; therefore, it is desired that this invention not be limited by the specific exemplary embodiments illustrated herein, but that it include all equivalents within the scope of the appended claims.

I claim:

1. The method for setting and disconnecting a drill string between a floating drilling platform and an underwater land formation, comprising assembling a shearing device for said drill string adjacent one end of a length of well casing, suspending said casing vertically in the water from said platform with said shearing device on the upper portion of said casing, connecting said shearing device to a source of actuating power on said platform, inserting a drill and drill string axially through the suspended casing and shearing device, drilling a hole in said platform while said casing remains suspended from said platform, lowering said casing from said platform and inserting said casing in said hole to a position where said shearing device is proximate to said bottom without withdrawing the drill string from said hole, cementing said casing in said hole, and actuating said shearing device from said platform to shear said drill string.

2. A device for closing the opening of a well during 1 an operation wherein an element extends from the surface of the earth axially through a casing aflixed in said well comprising a housing attachable to the casing, said housing having an opening therethrough in axial alignment with said casing and adapted to permit the passage of said element from said surface and into said casing, members mounted in said housing for movement relatively transversely across said opening into an abutting relationship, each of said members comprising a body element, a semicircular central portion in said body element and relatively movable thereto, a diametrically disposed surface on said central portion and positioned outwardly with respect to said body portion, a resilientpacking material between said central portion and said body element to form a seal against said housing when said members are moved under pressure into abutting relationship, a resilient packing material extending longitudinally across said diametrically disposed surface for sealing cooperation with the corresponding packing material on the other member, and a shearing blade affixed to the said diametrically disposed surface of said central portion and projecting outwardly of the said packing material thereon for shearing cooperation with the blade on the other member, each of said members defining an opening to receive the blade on the other member.

References Cited in the file of this patent UNITED STATES PATENTS 1,802,564 Lacey Apr. 28, 1931 1,802,565 Lacey Apr. 28, 1931 1,949,672 Barrier Mar. 6, 1934 2,512,783 Tucker June 27, 1950 2,592,197 Schweitzer Apr. 8, 1952 2,650,068 Rand Aug. 25, 1953 2,690,320 Shafier et al Sept. 28, 1954 2,808,229 Bauer Oct. 1, 1957 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION December 29, 1959 Patent Noo 2,919,111

Kingsley Mo Nicolson It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5, lineIf, after "hole in said" and before "platform While" n I line .35, insert bottom by said drill and drill string operated IIOIII said Signed and sealed this 31st day of May 1960n (SEAL) fittest:

KARL H, RIC LINE Attesting Officer ROBERT C. WATSON Commissioner of Patents 

